STREAM-CAPTURE IN MICHIGAN 



329 



Stopped, has already been noted. That of the upper section, near its 

 mouth, is shown in Fig. 3 — a view taken from the point B on the map 

 (Fig. i) and looking westward up the valley. 



The captured upper portion of Oak Ravine. — It will be noted that 



Fig. 3. — Oak Ravine — the deepened headwater valley of Oak Run. 



this upper portion has the sharp characteristics of youth. The side 

 slopes have angles as high as 25°. The stream in the bottom of the 

 valley has no flood-plain, but hurries over rapids and little falls, 

 giving evidence of decided youthfulness. Although pushed slightly 

 to one side or the other by the alluvial fans built forward from the 

 mouths of tributary gullies, it is in the main entirely competent to 

 care for the waste creeping into it. The depth of the ravine below 

 the upland is shown on the map at intervals of 250 feet by the num- 

 bers in the bottom of the ravine. It is seen from these numbers that 



